This invention relates to hypodermic needle assemblies of the type suitable for receiving and dispensing medication.
Various types of needle assemblies are known for receiving and dispensing medication. The needle assemblies are typically utilized with a syringe device including a hollow barrel and a plunger positioned within the barrel and operative in response to upward and downward movement of the plunger within the barrel to dispense fluid through the hollow shaft portion of the needle or withdraw fluid upwardly into the barrel through the hollow shaft portion of the needle. The lower end of the shaft portion of the needle is of necessity sharply pointed and as such presents a hazard whenever the point is exposed. Needle assemblies typically include a sheath which is cup shaped and which fits telescopically over the shaft portion of the needle with the upper end of the sheath suitably mounted on the base portion of the needle. In position, the cup shaped sheath totally shields the pointed end of the needle and prevents injury to users of the needle. Prior to use of the needle assembly, the shield is removed from the needle and the needle is utilized in known manner to either dispense medication or receive fluid. The sharp point of the needle is therefore exposed at all times following removal of the safety sheath until the needle assembly is ultimately disposed of, and it is not at all uncommon for puncture wounds to be inflicted by the exposed sharp point of the needle during the time between removal of the sheath and ultimate disposal of the needle assembly. Various devices have been proposed in the past to serve as a shield to protect the needle during and after use but these devices have either been ineffective in terms of performing their shielding function or have been unduly complicated with respect to their construction or their use. In any event, none of these needle shield devices have achieved any significant degree of commercial acceptance because of their ineffectiveness and/or complexity.